GB618421A - Improvements in or relating to electrical arrangements for converting from cartesian into polar co-ordinates - Google Patents

Abstract

618,421. Electric co-ordinate converters. DEHMEL, R. C. Oct. 24, 1945, No. 28041. Convention date, Oct. 25, 1944. [Class 40 (i)] Voltages representing the Cartesian coordinates of a point in a plane are applied to an electromagnetic device from which are inductively derived voltages corresponding to the equivalent polar co-ordinates. The invention is applicable to course charting devices for ships or aircraft or other moving objects. As applied to an aircraft trainer, sliders 33, 34, actuated by the trainer, take off from potentiometers 3, 4, energized from a transformer TR, voltages Ex, Ey, proportional to the x, y, Cartesian position co-ordinates of the simulated aircraft represented by the point 1 on the chart 5. The voltages Ex, Ey, which may be otherwise derived from the trainer are fed to the fixed quadrature windings 26, 26<SP>1</SP> of a rotary transformer 9 so that the secondary quadrature windings 25, 25<SP>1</SP> rotatable with the shaft 2 have voltages E#, Er induced therein representing the azimuth angle # and the range R multiplied by a factor dependent on the angular setting of the rotor. Voltage E# is fed through slip ring 28, brush 27, and amplifier 10 to the winding 29<SP>1</SP> of a two-phase servomotor 12, the other phase winding 29 of which is fed from the reference source Œe supplying the transformer TR. The servomotor rotates the chart 5 and the rotor 2 of transformer 9 through gearing 22, 23, 7, 8 until the rotor 2 and therefore the chart 5 take up an angular position corresponding to #, when E # is zero, or some other reference value dependent on bias applied to the amplifier 10. A second servomotor 16 has one winding 30 energized from the reference source and the other winding 30<SP>1</SP> energized through an amplifier 18 by the voltage Er. Motor 16 rotates the lead screw 15 to move the " range " nut 14 until the voltage Er is balanced in amplifier 18 by the voltage applied thereto by wiper 14<SP>1</SP>, moving with the nut 14, and derived from potentiometer 19 fed from a source of instant phase opposition to Er. The nut 14 thus moves the stylus 13 over the chart 5 according to the polar range R. The signalling elements 36, 38 of the trainer are driven from the azimuth and range elements 5, 14 respectively. Hunting of the servos may be prevented by velocity feed-back. The primary and secondary windings of transformer 9 may be reversed. D.C. motors may be used in lieu of the A.C. servos 12, 16 in which case the amplifiers 10, 18 must of course include demodulators. Specification 458,274 is referred to.